This invention relates to compositions of matter which are useful as catalysts, to a method for preparing these catalysts and to a method of using these catalysts. More particularly, this invention relates to catalyst compositions, to a method of preparing these catalyst compositions, to a method for polymerizing addition polymerizable monomers using the present catalysts.
In U.S. Ser. No. 8,800, filed Jan. 30, 1987 and now abandoned (published in equivalent form as EP 277,004) there are disclosed certain bis(cyclopentadienyl) metal compounds formed by reacting a bis(cyclopentadienyl) metal complex with salts of Bronsted acids containing a non-coordinating compatible anion. The reference discloses the fact that such complexes are usefully employed as catalysts in the polymerization of olefins. For the teachings contained herein the aforementioned U.S. Ser. No. 8,800 (now abandoned) and EP 277,004 are herein incorporated in their entirety by reference thereto.
Despite the utility of the catalysts disclosed in the above prior art references it is desirable to produce even more efficient and useful catalysts for addition polymerizations. In particular the present investigations have led to certain improved metal complex containing compounds that are highly active as polymerization catalysts and desirably allow for the polymerization of a wide variety of monomers and mixtures of monomers.
According to the present invention there is now provided a monocyclopentadienyl or substituted monocyclopentadienyl metal complex containing compound useful as an olefin polymerization catalyst corresponding to the formula:
CpMXn+Axe2x88x92
wherein:
Cp is a single xcex75-cyclopentadienyl or xcex75-substituted cyclopentadienyl group optionally covalently bonded to M through a substituent;
M is a metal of Group 3-10 or the Lanthanide Series of the Periodic Table bound in an xcex75 bonding mode to the cyclopentadienyl or substituted cyclopentadienyl group;
X each occurrence independently is selected from the group consisting of hydride, halo, alkyl, aryl, silyl, germyl, aryloxy, alkoxy, amide, siloxy, neutral Lewis base ligands and combinations thereof having up to 20 non-hydrogen atoms, and optionally one X together with Cp forms a metallocycle with M;
n is one or two depending on the valence of M; and
Axe2x88x92 is a noncoordinating, compatible anion of a Bronsted acid salt.
Such compounds are usefully employed in Ziegler-Natta type polymerization processes to prepare polymers for molding, film, sheet, extrusion foaming and other applications. The compounds may also be utilized in hydrogenation reactions, catalytic cracking and other industrial processes.